Phenobarbital Dosing

[ahicks51]

Speedy (5 yo male greyhound, ~75 pounds) was prescribed 90mg BID phenobarbital for seizures; his seizures- while sometimes prolonged- are quite mild. We suspect the underlying cause may be valley fever (coccidioidiomycosis); blood tests are negative, but apparently animals can have CNS involvement without antibodies in the blood.

 

By day 5, he was stumbling, having problems standing, ataxia, pacing. The vet was consulted, and he stated we should stay at that dosage. Vet has experience with greyhounds, and "inherited" a practice from a retiring vet with extensive greyhound experience.

 

Are greyhounds more sensitive to phenobarbital than other breeds? This poor guy won't get up because he doesn't have the hind-end coordination to do so, and then will pace for hours because he doesn't have the coordination to sit back down.

[MaryJane]

Have you consulted a neurologist - there are newer drugs that might be better in that there are less symptoms. This would include Keppra and zonisamide as well as others. My Lucy started on Zonisamide, and then a bit over a year later, we added Keppra, and then a year later we added Sodium Bromide (which I like better for greyhounds than the pheno - just my opinion). Lucy had very violent seizures and she would cluster however, she is under control now and barely ever has a seizure.

[LBass]

I'd second the idea of consulting a neurologist as well. Those are common Pb side effects and they do sometimes diminish as the hound's body adapts to the new medication, but it sounds as if he's too debilitated to wait for that possibility.

 

My own vet, bless him, called a neurologist for a consult and got some guidance on from him on what to prescribe for Piper's bad cluster events. Worked wonderfully and did not require a visit to the out of state neuro. Of course, that requires 2 vet's who are willing to cooperate.

Edited November 1, 2017 by LBass

[Fruitycake]

It's been many years since Monty (also 75 lbs) first went on pheno, but I know they started him at a higher dose at first before lowering it to the current 64.8 mg every twelve hours which he's been on for at least 8 years. I think he was on a higher dose for a few months.

 

When he first went on it at 1.75 years old we went through the drunk stage, but I don't think he was quite as bad as you have described and I'm not sure how much of Monty's drunkenness might have been from his hard-drive reboot (6 seizures in 24 hours caused some memory loss). I wonder if there might be any interactions with other meds he might be on, or if he's just individually more heavily impacted by it. I would maybe give it another week and have them test his blood levels and see if he could be lowered to the lower end of the thereapeutic range (Monty had been on the high side and his dosage was lowered because we asked for it and there was enough leeway for the dosage reduction). Or if paying for an extra blood test so soon isn't out of the question, see if they would do it now and find his values and adjust from there. It can be a while before things settle down if the biological system in question is excessively reactive (or unreactive) to the medicine in question.

 

Good luck! (And good to see you back!)

[tbhounds]

Thats a typical side effect when first starting pheno. I know there are other anticonvulsants available now but, many clinicians still prescribe pheno because its tried and true. Thats a heavy dose they have your dog on but, I can only assume they plan to reduce the dose. 64.8mg twice daily is a common dose for a dog of your size.

Edited to add-did a veterinary neurologist prescribe the pheno and are you returning for recheck blood work?

Edited November 1, 2017 by tbhounds

[ahicks51]

We're hopeful that a veterinary neurologist will not be necessary, because if it's not valley fever, the diagnosis is rather bleak; any additional diagnostic tests must be weighed against the costs to the adoption group and helping other dogs. If it *is* VF, then our hope is that the fluconazole will put it into remission, although CNS involvement with VF is quite serious. So I'm hoping to make the best with which we are given, and (first off) ensure the ataxia and other symptoms are from too much pheno (versus brain inflammation), and secondly to see if less pheno is an option.

[XTRAWLD]

To this day I still learn so dang much from this forum....

[MaryJane]

We're hopeful that a veterinary neurologist will not be necessary, because if it's not valley fever, the diagnosis is rather bleak; any additional diagnostic tests must be weighed against the costs to the adoption group and helping other dogs. If it *is* VF, then our hope is that the fluconazole will put it into remission, although CNS involvement with VF is quite serious. So I'm hoping to make the best with which we are given, and (first off) ensure the ataxia and other symptoms are from too much pheno (versus brain inflammation), and secondly to see if less pheno is an option.

 

Is it bleak because of the seizures - in many cases, seizures can be controlled although, it can take time to get the right mixture of seizure medications. Lucy is on 3 meds - NaBr, Zoni, and Keppra along with her cluster buster of rectal valium. Maybe provide more information on the symptoms that make this situation bleak. Also, it has been my experience that a neurologist will be more cost-effective over time than a regular vet.

[ahicks51]

It's bad because we've had him since March and these are the first seizures we've seen; between this and other symptoms, if it's not valley fever, then it's likely he will not be with us very much longer. Even if it is VF, CNS involvement is quite serious and can required prolonged- even life-long- prescription anti-fungal meds.

[Tracey]

Buttercup started having seizures last December. She's about 68 pounds and the vet started her at 64.8 mg twice a day. After increasing the dose over time the vet added potassium bromide, which messed her up something awful, so we discontinued that after a month. We maxed out (according to our vet) the phenobarbital at 113.4 mg twice a day, then added 300 mg of zonisamide twice a day as well.

 

It definitely takes some effort to get the right dosages and the right meds. If things don't improve, though, trust your instincts and insist on a different course of action.

[MaryJane]

It's bad because we've had him since March and these are the first seizures we've seen; between this and other symptoms, if it's not valley fever, then it's likely he will not be with us very much longer. Even if it is VF, CNS involvement is quite serious and can required prolonged- even life-long- prescription anti-fungal meds.

 

How is it bad ? Can you please describe symptoms - dogs can have both focal and full GM seizures. This sounds more and more like it needs a qualified neurologist to look at this boy.

[tbhounds]

I agree-neuro visit is a must. Sounds like you are not giving this hound much hope without a specialist opinion. There are so many reasons to cause seizures-not all are awful. Have you checked the thyroid function?

[HoundHeavenAZ]

Jimmie has been getting 64.8 morning and night along with potassium bromide and keppra for years. He gets thirsty, but not sloppy or drunk. Then he takes giant naps anyway so I honestly can't detect a reduction in energy

 

My vet has treated 3 epileptic greyhounds for me and is not hesitant to refer us to a neuro doc in the PhX metro area. We go to Celeste Flannery, Airpark Animal Hospital in Cottonwood. I'm sure she'd be happy to give you some contact info -- tell her Jimmie sent you

 

Happy to talk about it if you'd like.

 

Jody

 

[ahicks51]

The seizures are very mild and a secondary symptom. He has a blown right pupil and inflammation of the brain with negative bloods for infection and VF. It may be VF with CNS involvement such that there's a negative serum titer, but antibodies are present in the CSF. So, while treating with doxy (for an infection or latent TBD that's not showing up on a tick panel), prednisone (for the inflammation of the brain), fluconazole (for a potential VF infection), and phenobarbital for the seizures, I was hoping to find out whether or not 90 mg BID pheno is too much, and that seems to be the case.

 

He doesn't stop breathing during seizures, and he is often able to respond to his name while seizing. There is no rhabdo the next day, and his seizures are little more than head-nodding for a few minutes. While it is important that we control them, I find that drugging him to the point where he can't even move is excessive and the dosage seems high when compared to what others have used here.

 

We remain hopeful that the seizures are caused by VF since that can be treated, but the next step up is MRI- and, frankly, I don't know of any diagnosis via MRI that is going to be treatable.

[greysmom]

It does sound like too much to me. Loading doses are common, but this seems extreme - and each dog responds individually. How often is he having episodes?

 

Treatment of seizures in dogs is changing so rapidly that any one GP vet really can't keep up with all the latest moves. I nearly always recommend seeing a neurologist because of that. We had a seizure dog from 2003-2008, and then again a foster several years ago. The difference in treatment options and recommendations from the neuro vet was BIG! Pheno was not even the first drug the vet talked about due to the horrible side effects. It *is* much cheaper than the newer drugs though, so that might be a factor, especially for a foster.

[MaryJane]

The seizures are very mild and a secondary symptom. He has a blown right pupil and inflammation of the brain with negative bloods for infection and VF. It may be VF with CNS involvement such that there's a negative serum titer, but antibodies are present in the CSF. So, while treating with doxy (for an infection or latent TBD that's not showing up on a tick panel), prednisone (for the inflammation of the brain), fluconazole (for a potential VF infection), and phenobarbital for the seizures, I was hoping to find out whether or not 90 mg BID pheno is too much, and that seems to be the case.

 

He doesn't stop breathing during seizures, and he is often able to respond to his name while seizing. There is no rhabdo the next day, and his seizures are little more than head-nodding for a few minutes. While it is important that we control them, I find that drugging him to the point where he can't even move is excessive and the dosage seems high when compared to what others have used here.

 

We remain hopeful that the seizures are caused by VF since that can be treated, but the next step up is MRI- and, frankly, I don't know of any diagnosis via MRI that is going to be treatable.

 

 

Thank you for the detailed description, the blown right pupil does suggest "something happened" and I would think with that, the regular vet is going to be out of his/her comfort level here. The blown right eye could have also been caused by a head trauma so, I would think that the neurologist would be better at identifying what the symptoms are that the dog is having and more likely what is causing them. I'm not sure that the symptoms listed so far would be linked only with Valley Fever (my opinion). so again, I'm going to suggest again that the dog be seen by a neurologist as he can prescribe a med that might fit the situation better and also provide a long term diagnosis. While many neurologists like to have an MRI - it is not necessary to start treatment for the symptoms. As you said and I agree, getting the diagnosis does not necessarily mean that you would treat (brain tumor). Lucy's first neurologist was pretty blase about the MRI suggesting that if it was a tumor, we would know within 1 year, maybe 18 months as the symptoms would progress. Lucy's consult with her neurologist(s) usually run under $200 and have been well worth it.

 

Whereas the MRI might not be necessary, I might think that a neurologist might want to do a CSF(spinal fluid) to see eliminate Valley Fever. That should only be done by a neurologist and I think I was quoted about $300 but, that was with the MRI.

 

In this case, there are other drugs that might be a better choice for the seizures - ones that have less of a "doping effect".

 

If travel to a neurologist is an issue, some of the teaching hospitals around the country might be set up to do a video consult and could work with your vet.

[DustysMom]

Just FYI, my first three VF tests came back negative. The fourth was very high positive. Thinking good thoughts for your boy

[ahicks51]

Sad ending, so stop reading now if it'll be upsetting.

 

Speedy started to decline and was euthanized Monday despite vet neuro consult on Friday and some slight modifications to his meds. The pheno didn't seem to be causing his ataxia and other symptoms, or at least they didn't improve substantially even after we reduced the dose. The vet wasn't convinced Speedy was even having seizures; the (lousy) video we provided, along with our observations, suggested he had tremors or wobbling, versus a seizure. He sure as heck behaved post-ictal after his tremors, so I don't know what to think.

 

We would have let him go sooner but for how we held out hope it was valley fever with CNS involvement, and that the fluconazole might take hold in time. He remained a strong eater up until the end, although he had substantial difficulties in other parts of his life. I don't think there was much pain, but can't be certain. Ultimately, based on what we know, it could have been meningitis or encephalitis (which might have responded to the steroids), tick borne (he was negative for all TBDs and was also on doxy), valley fever (despite having been on fluconazole for 10 days, fluconazole doesn't get into the CNS very well), or a brain tumor. Vet neurologist determined symptoms and behavior when tested put the location of whatever problem (inflammation, tumor growth, etc.) at the base of the brain stem, suggesting it was a brain stem tumor which would be consistent with the slow, gradual changes in behavior we saw.

 

Six hours after putting him down, I asked the vet clinic if they'd do a CSF draw to send out for a valley fever titer (his bloods were negative, but the CSF can contain antibodies without systemic involvement), but there was some mumbo jumbo about how they couldn't vouch for how the body was stored and since I'd signed away any necropsy, they said they would refuse to do so. As if antibody levels would change in CSF in cold storage after euthing. As if even a false positive or a false negative would matter at this point. So, lesson learned- even if the euthing is an emergency, if the cause of the illness is unknown leave the option for testing open even if no full necropsy is done.

 

Since Speedy was a foster, we adopted him posthumously. It's devastating for all parties involved.

Edited November 8, 2017 by ahicks51

[Batmom]

I'm so sorry. It sounds like letting him go was the best thing for him but certainly miserable for you and his other friends.

 

Godspeed, Speedy.

[MaryJane]

I'm so sorry that this turned out this way. It sounds like you were doing everything that you could to help this boy. Sometimes, no mater how hard we try or what we do, it just isn't going to turn out the way that we would like.

[LBass]

I'm so sorry Speedy's last days were so difficult for him and for those who love him. Fare thee well, Speedy.

[GreyAcresMom]

Hey Aaron. I,just tried to sent you a PM but said you couldn’t receive messages.

 

I was just asking about you...not even a week ago.

 

Hope all is well. Send me a message so I can find you on FB.

[Guest Linda12]

​Just consult a neurologist once. It will be really helpful.